Sigma EF500 DG Super + Canon EOS 10D

Camera settings were ISO 400, partial metering, centre focus point selected, "M" mode, 1/125s, f/5.6. Flash exposure lock was used for all images.

  Straight ahead Reflected in ceiling
With Omnibounce Omnibouce, straight ahead Omnibouce, toward the ceiling
Naked flash Naked flash, straight ahead Naked flash, toward the ceiling

For comparison, here is the same scene shot in natural light (1/2s, f/5.6

Natural light